An Active Atlantic, Typical for Late August

So, if you're not quite fatigued from hearing about Invest 99L yet, then you may be after you see all the systems we are watching now. First, we will start with a system that is already named... Gaston.

TROPICAL STORM GASTON

Gaston has been fighting off some wind shear over the past couple of days, it is starting to re-strengthen yet again. Thankfully, Gaston is expected to remain over the open waters of the Atlantic and not impact any land areas directly over the next 5 days.

As you can see, Gaston will not be making landfall anywhere through at least the next 5 days, but it will become a hurricane yet again as it moves over the open Atlantic.

DISTURBANCE IN THE NORTHWEST GULF OF MEXICO

The disturbance being monitored here is just off the coast of Texas and Louisiana. This trough of low pressure has a near zero chance of development as it moves onshore Sunday. This is the latest from the National Hurricane Center:

A weak trough of low pressure located south of the coast of
southwestern Louisiana is producing disorganized shower and
thunderstorm activity over the north-central Gulf of Mexico.
Conditions are not expected to be conducive for development before
this system reaches the coast of Texas on Sunday.  However, heavy
rainfall is possible along the Gulf Coast from Louisiana to
southeastern Texas during the next few days.  For additional
information, please see products from your local National Weather
Service office.
* Formation chance through 48 hours...low...near 0 percent
* Formation chance through 5 days...low...near 0 percent

While it isn't expected to develop, we are looking at more unwanted rain for southern Louisiana and southeastern Texas.

INVEST 91L

Yes, we do have another area of investigation from the National Hurricane Center. This is 91L located to the southwest of Berumda. It has a pretty vigorous low level circulation, but the convection is being sheared.

The latest from the National Hurricane Center says:

A broad area of low pressure located about 140 miles southwest of
Bermuda is producing winds of 30 to 35 mph.  Shower and thunderstorm
activity has not become any better organized during the past few
hours, and significant development of this system is likely to be
slow to occur due the proximity of dry air during the next couple of
days while it moves westward and then west-northwestward at about
10 mph toward the coast of North Carolina.  After that time,
increasing vertical wind shear is expected to make development
unlikely.  For additional information on this system, see High Seas
Forecasts issued by the National Weather Service.
* Formation chance through 48 hours...low...30 percent
* Formation chance through 5 days...low...30 percent

Models generally agree on taking 91L west-northwestward toward the North Carolina coast and Outer Banks before slinging it back out into the Atlantic. If 91L develops, it probably won't be anything too strong, but it will likely bring some heavy rainfall to parts of North Carolina.

INVEST 99L

Yes, we are still talking about this thing. Bless its heart. It really is trying. It actually looks better than it has in recent days, but looks can be a bit deceiving. Some observations from earlier suggest that a low-level circulation was trying to form, but it was displaced from the mid-level center, shearing some of the convection. Also, now we have thunderstorms firing over Cuba, part of the daytime hearing, which is taking away energy from 99L. So, development chances, for right now, don't look all that great. The latest from the National Hurricane Center says:

A weak area of low pressure located between the northern coast of
Cuba and Andros Island in the Bahamas continues to produce a large
area of disorganized showers and thunderstorms, mainly to the south
and east of its center.  Upper-level winds are not conducive for
significant development during the next day or so while the low
moves west-northwestward through the Straits of Florida at about 10
mph.  Environmental conditions could become a little more conducive
for some development when the system moves into the eastern Gulf of
Mexico early next week.  Heavy rains are likely to continue over
portions of eastern and central Cuba today.  Gusty winds and locally
heavy rainfall are likely over portions of the Bahamas, and will
spread into parts of southern Florida and the Florida Keys by
Sunday.  Interests elsewhere in Florida and the eastern Gulf of
Mexico should continue to monitor the progress of this disturbance.
The Hurricane Hunter aircraft mission scheduled to investigate this
system today has been canceled.
* Formation chance through 48 hours...low...30 percent
* Formation chance through 5 days...medium...40 percent

So, while development chances are lower than they have been, they still are not zero. You can never say never when it comes to the tropics in late August. Now, it looks a little better, but does that mean we have a little better handle on where it's going?

For the first 48 hours, somewhat yes. After that, still no idea. We are pretty confident that 99L will pass through the Florida Straits into the southeastern Gulf of Mexico. After that, as has been the case for the last several days, the models wildly diverge in both track and intensity. Now, the one thing the models do agree on is that there will be a more favorable environment for some sort of possible development. So, it is possible for 99L to get into the Gulf and try to organize itself. But, once again, we are still talking about a system that is not organized. So, really, the models cannot be fully trusted beyond 48 hours, giving us a rather low confidence in any sort of forecast. Our two most reliable models (GFS and ECMWF) have been at odds with each other for a while now. Let's take a look at their 00Z runs from last night.

So, on top we have the 00Z GFS running out through 7 PM Sept. 1, and below it we have the 00Z ECMWF running out through the same time. Now, neither the GFS or the ECMWF really develop 99L. The GFS actually splits 99L with part of the energy left drifting west in the Gulf of Mexico and another part developing off the northeast coast of Florida.

The ECMWF doesn't really develop it either. It kind of makes 99L an elongated system that extends from the central Gulf into the southeast. Somewhat similar, a d both showing weak solutions. So, small victories for some agreement, right? Now, let's see if the models changed 12 hours later.

So, these are the 12Z runs of the GFS (top) and the the ECMWF (bottom). No the go out to 7 AM Sept. 1. Let's look at the GFS first. The GFS is a little stronger with this run than its 00Z run. It takes 99L up the west coast of Florida, then sort of merges it with 91L before sending it out to sea.

The ECMWF is a completely different story. It shows 99L a good bit stronger than the GFS's runs and its own 00Z run. It takes 99L west into the central Gulf and kind of stalls it. There are reasons I'm not showing beyond this time frame:

1. It's beyond 5 days out.
2. The end of the 12Z run of the ECMWF probably should not be seen.

But, the GFS has one thing going for it. It has decent run-to-run consistency. I won't say it's good, but it's okay. It continues to show something weak that (at least in part) affects the west coast of Florida. The ECMWF does not have good run-to-run consistency. It keeps jumping from weak to strong and shifting the track back and forth.

However, the models can and will change, as we've seen over the past several days. I think once it gets into the Gulf, we will have a better idea of what it will do.

TROPICAL WAVE COMING OFF OF AFRICA NEXT WEEK

Nope, we aren't through yet. We now turn our attention to western Africa for the next potential tropical system.

So, I know I told you I didn't want to show you anything past Day 5 on models, but I'm going to break that rule here. There has been some good agreement on a tropical wave emerging from Africa on Tuesday. Above are the 12Z GFS (top) and ECMWF (bottom) out to 7 AM Sept. 6. Now, the models have consistently shown this and are in pretty good agreement out to Day 8 or so, which is pretty rare. But, if this wave holds together, there are pretty good indications that it could develop into the next named storm (Hermine, Ian, or Julia, depending on if 99L and/or 91L get named). This is still about 3 to 5 days out,  it this is what the National Hurricane Center is saying:

A tropical wave is expected to move offshore of the west coast of
Africa on Tuesday.  Conditions appear favorable for development of
this system later next week while it moves westward at 15 to 20 mph.
* Formation chance through 48 hours...low...near 0 percent
* Formation chance through 5 days...low...30 percent

So, again, with all this said, just stay up-to-date with your official sources. Anything can change, but just stay aware and stay prepared as we are now (basically) in the peak of hurricane season.


Again, credits go to Levi Cowan and his website, Tropical Tidbits, for all the forecast images.